In the microprocessor industry, formerly each next iteration of a product used to be characterized by noticeably better performance due to significant increases in both clock speed and part count. Each next product generation also had greater power consumption, and consequently, increased heat output [Chen, C., and Lu, T. J. Thermal Transport and Fire Retardance Properties of Cellular Aluminum Alloys. Acta Mater, 1999, vol. 47(5)]. This necessitated the application of more powerful cooling systems.
Heat-sinks had to be increased in size and forced convection replaced passive cooling, adding a fan to every heat-sink [Republic of Korea Patent No. KR20030085737]. Mesh or foam heatsinks, and microchannels are being studied, and although when compared with a standard finned heatsink they exhibit better use of space. A forced convection heat dissipating potential of the heat sink alone is still inadequate for potential heat output of modern and future microprocessors, and like devices [U.S. Pat. No. 7,219,715]. Improvements in thermal pastes, packaging, and heat spreading continued, but the next big step was debated [Wilson J. and Guenin B. Cooling solutions in the past decade, Electronics Cooling, 2005, vol. 11(4)]. Popular leaps contemplated included the use of mediums besides air, namely water, low-boiling point hydrocarbons, liquid metals and alloys, and cryogens [Lasance, Clemens J. M. and Simons R. E. Advances in high-performance cooling for electronics, Electronics Cooling, 2005, vol. 11(4)].
Heat-sinks incorporating thermoelectric elements and similar schemes are already available on the market, and despite being solid-state units, are nevertheless not widely used due to limited heat dissipation relative to power consumption [US Patent Application Publication No. 2007/0079615]. Heat-sinks incorporating thermosyphons, where refrigerants are boiled at a higher than ambient temperature and then passively condense, are widely used as aftermarket heat-sink products (that are not usually bundled with electronics components.) For heat pumping from an enclosed space to another point in the system, or for better area-of-effect heat spreading from a point, these systems allows for complex heat sinking assemblies and better heat dissipation relative to power consumption, at an additional monetary cost [U.S. Pat. No. 7,149,086].
The boiling of cryogens displays greatest heat dissipation versus time [U.S. Pat. No. 7,243,507]. Unfortunately, it is often challenging to offer the equipment needed for that type of setup outside an industrial setting; cost of items, cost of use, skill to maintain, and system bulk are prohibitory [U.S. Pat. No. 6,070,414]. That a cycled cryogenic cooling system is preferable in such circumstances is a further complication [U.S. Pat. No. 5,647,217 and U.S. Pat. No. 5,333,460]. The same, to a lesser degree, can be said to have stalled the total widespread use of relatively more affordable water cooling and refrigeration. In a mandatory mass deployment (of the new cooling equipment), by computer system builders the service cost alone would alienate much of the end-user market, and yet, available so-called mainstream alternatives that could be bundled with products were inherently limiting.
In response, hardware manufacturers adopted a new production process strategy: to increase the overall number of processors while lowering clock speed per processor [U.S. Pat. No. 7,043,405]. With heightened precision of manufacturing, this strategy was swiftly realized in the form of so-called multi-core processors, where multiple otherwise self-contained processors, or cores as they are called, exist on a single processor die. Provided the continued support of the software sector, the practice appears to have thus far been successful.
Regardless, whether clock speed increases or increases in part count through an increase in the number of processor cores, increased heat output is eventually unavoidable if there is to a an increase in performance. Besides a consumer's demand for greater performance, there is also a continued demand for mobility, which are goals at opposite ends of a spectrum when concerned with electronics cooling. Furthermore, whereas high power consumption is common in the workstation or server application, it is unacceptable in mobile platforms, where the conflict may not necessarily lay in the cost of use but more so in that access to a sufficient power source is likely impossible.